To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation and the like.
In the 5G system, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
There are two types of relay end networks in a wireless communication system. First, a layered network is a network that can decode one transmission packet for each reception block. In the case of the layered network, a receiving end performs graph-based simultaneous decoding for the entire trajectory of a received signal. In the simultaneous decoding, the receiving end performs MAP decoding in consideration of codes and observation components that are used by a transmitting end, a relay end, and a receiving end. The receiving end forms an entire factor graph in order to perform the MAP decoding. Second, a non-layered network is a network in which one reception block receives several pieces of packet information intermingled with one another. In the case of the non-layered network, a receiving end performs sequential decoding. The receiving end restores a received message by performing successive cancellation decoding and then bringing interference into noise in consideration of signals received through a relay end.
When the receiving end performs sequential decoding, the receiving end sequentially performs two-phase reception operations and thus loses information in each decoding step. The sequential decoding has a problem in that performance is degraded on account of the loss of information. When the receiving end performs simultaneous decoding, the receiving end performs decoding on all transmission blocks of the entire network. Since the receiving end performs the decoding on all the transmission blocks, complexity increases, and a delay in the reception of a signal happens. Namely, the sequential decoding has a problem of performance degradation caused by the loss of information. In addition, the simultaneous decoding has a problem in that the reception of a signal by means of a receiver is delayed.